In any pressurised vessel, the wall of the vessel represents a barrier between a region of relative high pressure and a region of relative low pressure. If the wall becomes breached there is typically a rapid transit of material through said breach as the two regions regain equilibrium.
This can have disastrous consequences, particularly in the field of boats and submarines where the transitting material is fluid (e.g. seawater) and can result in the vessel sinking. Submarines are of particular concern, as the water pressure increases with depth and gives a higher differential between the areas of relative high and low pressure, and this increases the rate of fluid transit in the event of a breach. Consequently, breaches must be repaired with urgency.
Presently, as is known in the art, breaches may be repaired temporarily with a set of bungs or dowels. Typically, the set of bungs are formed of wood or a plastics material with the bungs being of varying sizes to repair correspondingly sized breaches. When a bung is inserted into the breach, access to the hole is blocked and so for a full repair the vessel must be removed from the water (dry-docked) and the bung can be safely removed and the hole repaired.
Clearly, this known method of repairing breaches has a number of drawbacks. Firstly, a number of bungs must be carried on the vessel to accommodate different sizes of breach, which is inconvenient and can prevent the repairing of a second breach if the appropriately sized bung is already being used to repair a first breach. A given bung may only be used to repair a hole that closely matches the size of that particular bung. Having a plug that can be used to repair holes of various sizes would overcome this drawback.
Additionally, the bungs block access to the damaged area in use. This has the drawback that a full repair must be postponed until the vessel makes it back to the dock. This is risky, as bungs are held in place with mechanical force, and only friction prevents the bung from being pushed out of the hole. Consequently, bungs can fail if they are left in the breach for an extended period. Also, often a bung must be hammered into a breach to ensure a snug fit. This can put stresses on fault lines surrounding the breach, weakening these areas and risking failure of hull integrity. It would be beneficial to provide a plug that continues to provide access to the hole for repair in use. It would also be beneficial to provide a plug that does not require hammering to remain in place.
Other prior art apparatuses comprise ‘umbrella’-type plugs, such as those disclosed in GB2432562, GB2217591 and GB1450861. These comprise sealing members which are inserted through the hole in a collapsed state and then expanded over the hole by the action of support struts, the sealing means then being clamped over the hole. These devices may be inserted through the hole from the region of relative low pressure, however to withdraw them back requires the sealing means to be collapsed again, which is not always feasible. Damage to a support strut can cause the sealing means to be locked in an expanded state, making the apparatus irretrievable through the hole. Said umbrella-type plugs also have the drawback that they rely on mechanical operating mechanisms to expand the sealing member—see, for example FIG. 2 of GB2432562, FIG. 5 of GB2217591, and FIG. 1 of GB1450861. If the operating mechanism fails the sealing member may cease to prevent the transit of material through the hole. This means that these types of plug have a risk of structural failure (a breach in the sealing member itself), plus an additional risk of mechanical failure. These umbrella-type plugs also suffer from the drawback that they must be installed with two hands: one to hold the plug and one to operate the mechanism. This can be a difficult operation to perform in confined spaces where access to the hole is restricted. It would be beneficial to provide a plug that can be inserted into, and retracted from, a hole with one hand.
As other prior art may be mentioned, DE20204880U, DE19957445, FR2574890, SU1110718, FR2259009 and US5845 all disclose various known apparatuses for sealing holes in walls which divide a region of relative high pressure from a region of relative low pressure.
The present invention aims to provide a sealing apparatus capable of overcoming the aforementioned drawbacks.